Because stencil buffers can now be texture sampled, used in
cubemaps, blitted, etc, the quadLayout used for stencil
buffers requires constant texture coordinate conversion in
order to perform various tasks involving stencil buffers.
For now, the simplest solution is to remove the quadLayout
used by the stencil buffer.

Fixes all issues in the following subcategory using SwANGLE:
dEQP-GLES31.functional.stencil_texturing.format.*_stencil8_cube

Bug: b/144353295
Change-Id: I2a8cbdda0036146f9dca222ec330841788a3ee8b
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38188
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>